1. Field of the Invention
The present invention relates to a thin film deposition apparatus, and particularly to an improved thin film deposition apparatus which allows easy increasing of the temperature of a crucible by using low electric power, for thus reducing the maintenance costs of the apparatus, and which can be used to fabricate a uniform thin film because there is very little variation of density of the manufactured thin film device, whereby the thin film deposition apparatus has a compact structural design which allows easy maintenance and repair.
2. Description of the Conventional Art
Recently, as technology advances, products have become lighter and smaller in size.
As common methods for fabricating a light and small-sized product, a vacuum deposition method directed to depositing metal atoms which are neutral state under a vacuum, an ion plating method, a sputtering method, a chemical vacuum deposition (CVD) method, etc. are used.
However, in the vacuum deposition method, since the metal in neutral state is attached to the substrate by means of only a thermal energy, the adhesive force of the metal with respect to the substrate is very weak. The ion plating method has a better adhesive force compared to the vacuum deposition method; however, the quality of the thin film is degraded. In the sputtering method, the composition ratio of the thin film disadvantageously varies due to a matrix effect. In the CVD method, because an organic chemical material is used, the thin film is contaminated, and the quality of the thin film is degraded, for thus causing malfunctions of the device.
Among the many methods directed to overcoming the weak adhesive force problem between the substrate and the deposited thin film, the problem of contamination of the thin film, and the problems of non-uniformity of the thin film, a partially ionized beam deposition (PIBD) method is known as the best method in the industry. Namely, the PIBD method is directed to improving the adhesive force between the substrate and the thin film using the energy within ions by simultaneously scanning a metallic vapor and metallic self-ions in vacuum state.
Here, in the PIBD method, the most important element is the ion source which generates the metallic ions. This ion source requires the following characteristics:
1) The temperature of the crucible for the ion source should be allowed to be substantially increased for depositing various kinds of metallic ions. PA1 2) The temperature of the crucible must be increased by using low electric power, and the ionization rate should be increased thereby as well. PA1 3) The ion source should be able to operate stably for a long period of time, and detachment of the crucible and parts of ion source and easy maintenance should be possible in order to deal with problems such as insulation breakage caused by the deposition of metal on the depletion of the source material. PA1 4) The uniformity of the ion beam should be high in order to enhance the reliability of the deposited thin film.
FIG. 1 is a cross-sectional view illustrating a conventional thin film deposition apparatus. As shown therein, a vacuum chamber 1 includes a crucible 2 provided for vaporizing a metallic material. An ionization section 3 is disposed therein for ionizing the vapor state metallic material, and an acceleration section 4 is disposed therein for accelerating the metal ions.
In the drawings, reference numeral 1a denotes a vacuum outlet, 2a denotes a nozzle, 5 denotes a substrate holder, 6 denotes a filter (a grid), 8 denotes an anode, 9 denotes a crucible heating filament, and 10 denotes precipitates (metallic source material).
However, the conventional metallic thin film deposition apparatus has disadvantages in that the uniformity of the ion beam is degraded, and the efficiency of the apparatus is low.